Ignition system for multiple fuel burners



P 1955 H. w. RICE ETAL 2,705,531

IGNITION SYSTEM FOR MULTIPLE FUEL BURNERS Filed Jan. 6, 1951 2She'ts-Sheet 1 INVENTORS Harold Wflz'ceqzd By lbbe t C-Mauz.

THEIR ATTORNFY' April 5, 1955 H. w. RICE ETAL IGNITION SYSTEM FORMULTIPLE FUEL BURNERS Filed Jan. 6, 1951 2 Sheets-Sheet 2 INVNTOR HanoiW Ewq qmd BY Robert C. Mauz.

YWHR AFWGQYEY United States Patent IGNITION SYSTEM FOR MULTIPLE FUELBURNERS Harold W. Rice, Los Angeles, and Robert C. Main, San

Gabriel, Calif., assignors to Robertshaw-Fulton Controls Company,Greensburg, Pa., a corporation of Delaware Application January 6, 1951,Serial No. 204,792 2 Claims. (Cl. 158-124) This invention relates toignition systems for fuel burners and more particularly to electricallyoperated systems for multiple fuel burners.

Systems of the type indicated have been arranged so that a switch may beclosed to energize an igniter circuit when a manually operable valve isopened to admit fuel to a burner. The fuel is then ignited by theelectric igniter andatter the expiration of a starting period theigniter is disconnected by the operation of a timing device. It 1sapparent that controls for multiple burners would involve the use of aplurality of switch actuating and tim ng mechanisms and that the cost ofa multiple burner ign tion system would be substantially reduced if asingle tim ng mechanism were made to serve a number of igniters. It is aprincipal object of this invention to provide an ignition system whereina multiplicity of electric igniters are controlled by a single timingmeans.

A preferred embodiment of this invention takes the form of a gas rangewith electric igniters for the top and oven burners connected inparallel and the energization of the igniter circuit under the controlof a relay operated main switch. A number of normally open switches arerespectively associated with the fuel control valves to be closed whenthe valves are opened, the switches being connected in parallel and theparallel switch circuit being connected in series between a source ofelectric current and the relay coil so that closure of any one of theseswitches will energize the coil to actuate the main switch and energizethe igniter circuit. A holding circuit, completed upon closure of themain switch, maintains a voltage across the relay coil until the holdingcircuit is broken by a timing device. To prevent energization of theoven igniter each time a top burner igniter is energized, a switch isconnected in series with the oven igniter and is connected to the ovenburner supply valve in such a way that it is closed only when the valveis in open position. Thus, as will appear hereinafter, the necessity ofa timing device for each igniter is eliminated.

Another object of this invention is to provide a simple ignition systemincluding a single timing mechanism and a plurality of electric igniterswherein the igniters may be selectively energized.

Other objects and advantages will become apparent from the followingdescription taken in connection with the accompanying drawings wherein:

Fig. 1 is perspective view of a fuel supply and ignition apparatus forgas range top and oven burners embodying this invention; and

Fig. 2 is a wiring diagram for the apparatus of Fig. 1.

Referring more particularly to Fig. 1 of the drawings, the ignitionapparatus is shown in connection with a cooking range having the usualoven burner and top burners 12, 14, 16 and 18. As is customary inequipment of this nature, the various burners receive fuel from amanifold 20 connected to a source of fuel supply.

The main oven burner 10 is supplied with fuel from the manifold 20 by afuel pipe 22 and the fuel supply there in is under the control of meanscomprising a fuel cock 24 which may also embody the usual thermostaticcontrol device adjustable, together with the cock 24, by a knob 26 andbeing responsive to temperatures in the oven where the burner 10 islocated. As combined fuel cocks and thermostatic control devices arewell known, further description is deemed unnecessary.

The flow of fuel in the pipe 22 to the oven burner 10 is also under thecontrol of a safety shut-off device,

2,705,531 Patented Apr. 5, 1955 designated generally by the referencenumeral 28, here shown as being responsive to the presence of a flame ata pilot burner 30 disposed in lighting relation with the oven burner 10.The safety shut-off device 28 may be of any known type and includes athermal element 32 disposed adjacent the pilot burner 30 to be subjectedto the heat of a flame emanating therefrom. The pilot burner 30 issupplied with fuel from the manifold 20 by a conduit 34, the supply offuel therein being under the control of the fuel cock 24 but not underthe control of the thermostatic control device associated with the cock24 in a manner well known in the art.

Means are provided for supplying fuel to the top burners 12, 14, 16 and18 and since the structure and operation of each means is similar to theother, a description of one will suffice to show the structure andoperation of all. Corresponding parts of such similar means aredesignated by corresponding reference numerals followed by the suffixesa, b, and 0 respectively.

The top burner 14 may be supplied with fuel from the manifold 20 by afuel pipe 36 and the fuel supply therein is under the control of a cock38 manually operable between open and closed positions by means of aknob 40.

Fuel issuing from the top burners 12 and 14 is adapted to be ignitedthrough corresponding flash tubes 42 by an electric resistance igniter44 and similarly fuel issuing from the top burners 16 and 18 is adaptedto be ignited through similarly corresponding flash tubes 42 by anelectric resistance igniter 46. Fuel issuing from the pilot burner 30 isadapted to be ignited by an electric resistance igniter 48. As will morefully appear, energization of the igniters 44, 46 is under the controlof switches 50, 50a, 50b, and 500 operatively associated with cocks 38,38a, 38b, and 38c respectively, and energization of the igniter 48 isunder the control of switches 52 and 62 operatively associated with thecock 24.

Referring now to Fig. 2, the igniters 44, 46 and 48 are shown as beingconnected in parallel across wires 56 and 58 connected to the upper andlower terminals respectively of the secondary winding of a step-downtransformer 60. A switch, indicated generally by the reference numeral62, is connected in series with the oven burner igniter 48. It will beapparent that if electric current is supplied to the primary winding ofthe transformer 60 the above described circuit including the igniters44, 46 and 48 will be energized to permit the igniters to perform theirigniting function.

The primary coil of the transformer 60 is connected to a source ofelectrical energy by wires 64 and 66 under control of a main switch 68.The main switch 68 is adapted to be actuated by control means or a relaydesignated generally by the reference numeral 70. The control relay 70is of the electromagnetic type having a solenoid winding 72 and amovable core 74 cooperable therewith. The movement of the core 74 toattracted position is designed to operate the main switch 68 to itsclosed position to connect the primary winding of the transformer 68with a source of commercial current here shown as line wires L1 and L2.

Movement of the core 74 of the relay 70 to attracted position is alsoadapted to operate a time delay switch 76 which will open after aspecified time delay and have an instantaneous reset characteristic. Theswitch 76 is preferably of the mercury tube type well known to thoseskilled in the art and is so indicated in the drawing. The switch 76 isarranged to be closed when the core 74 of the relay 70 is in itsunattracted position and to open after a predetermined time delayfollowing movement of the core '74 to its attracted position. The switch76 is provided with a pair of electrodes 78, 80 and an electricalconnection is established therebetween by a body of mercury 82 when thecore 74 of the relay 70 is in its unattracted position.

Means are provided to maintain the main switch 68 in its closed positionin order that the igniters 44, 46 and 48 will remain energized to effectfuel ignition. This means takes the form of a holding circuit which iscompleted when the main switch 68 is moved to the closed position andmay be traced as follows: line wire L1, wire 84, electrode 78 of timedelay switch 76, body of mercury 82, electrode 80 of time delay switch76, wire 86, solenoid winding 72 of relay 70, lower switch blade of mainswitch 68, and wire 88 to line wire L2. Since the holding circuit thustraced includes the time delay switch 76, the time delay switch 76 willbreak the holding circuit after a predetermined period to provide aneffective means for setting the period during which the igniters 44, 46,48 will be energized as will more fully appear.

Means are provided for causing the control relay 70 to close the mainswitch 68 when any one of the cocks 24, 38a, 38b, or 380 is moved fromthe closed to an open position. These means may comprise the switches50, 50a, 50b, 50c, and 52 connected in parallel between wires 90 and 92,wires 90 and 92 being connected to the solenoid winding 72 of the relay70 and to the Wire 88 respectively. Each of the switches 50, 50a, 50b,50c, and 52 are identical and a description of one will suffice to showthe structure and mode of operation of all, corresponding parts ofsimilar switches being designated by corresponding reference numeralsfollowed by the suffixes a, b, c and d respectively.

The switch 50 includes an element 94 rotatable with the knob 40 and gascock 38 and a cam element 96 is carried by the element 94. The camelement 96 is adapted to engage a resilient switch arm 98. The switcharm 98 carries a contact 100 which is adapted for operative engagementwith a relatively fixed contact 102 when the knob 40 is rotated fromclosed toward open position. It will be apparent that the engagementbetween the contacts 100 and 102 is momentary only and that the camelement 96 will slip past the resilient switch arm 98 upon furtherrotation of the knob 40. Moreover, when the knob 40 is rotated in thereverse direction, the contacts 102, 100 cannot become engaged.

When the contact 100 engages the contact 102 a circuit is established asfollows: line wire L2, wire 88, wire 92, wire 104, contact 102, contact100, resilient switch arm 98, wire 106, wire 90, solenoid winding 72 ofcontrol relay 70, wire 86, electrode 80 of time delay switch 76, body ofmercury 82, electrode 78 of time delay switch 76, and wire 84 to linewire L1. Thus, the solenoid winding 72 of the control relay 70 will beenergized to move the main switch 68 to the closed position to energizethe primary winding of the transformer 60 and complete the holdingcircuit of the control relay 70 as hereinbefore described.

The rotatable element 94d, associated with the oven burner cock 24 maycarry a second cam element 108 adapted to operate the switching means 62during rotation of the knob 26 between closed and open positions.

The switching means 62 may comprise a toggle arrangement having a switchlever 110 pivoted intermediate its ends and engaged by a coil spring 112for causing the switch lever 110 to remain in the position to which ithas been moved. Thus, upon rotation of the knob 26 in a counterclockwisedirection from closed to open position, the cam element 108 will engagethe switch lever 110 and cause rotation thereof on its pivot in aclockwise direction. When this movement is completed, the switch lever110 makes engagement with a relatively fixed contact 114. When the knob26 is rotated in the reverse direction, the switch lever 110 is movedout of engagement with the contact 114 by the cam element 108 and, underbias of the spring 112, will remain in contact disengaged position untilthe knob 26 is again rotated in counterclockwise direction.

In the operation of the apparatus, assuming that there is no flamepresent at any of the burners and that it is desired to ignite a topburner, one of the knobs 40, 40a, 4017, or 400 is rotated in acounterclockwise direction to admit fuel to the burner associatedtherewith. One of the switches 50, 50a, 50b, 500 is momentarily closedto energize the solenoid coil 72 of the control relay 70 to cause themain switch 68 to be moved to the closed position thus energizing theprimary winding of the transformer 60 and completing the holding circuitof the control relay 70. Current will now flow through the igniters 44,46 and their temperatures will be raised sufficiently to cause ignitionof the fuel. At the expiration of a period of sufficient length topermit fuel ignition to take place, the time delay switch 76 willinterrupt the holding circuit of the control relay 70 permitting thecore 74 to move to its unattracted position. Movement of the core 74 tothe unattracted position opens the main switch 68 to break the supplycircuit for the primary winding of the1 transformer 60 and thusdeenergize the igniters 44 an 6.

If it is desired to ignite the oven burner 10, the knob 26 is rotated ina counterclockwise direction to open the cock 24 to admit fuel to thepilot burner 30 through the conduit 34. Switch 62 will be closed toconnect the igniter 48 across the terminals of the secondary winding ofthe transformer 60 to a circuit which may be traced as follows: lowerterminal of the secondary winding of the transformer 60, wire 58, wire116, contact 114, switch lever 110 of switch 62, wire 118, igniter 48,wire 120, and wire 56 to the upper terminal of the secondary winding ofthe transformer 60. counterclockwise rotation of the knob 26 will alsocause momentary closing of the switch 52 to cause operation of thecontrol relay 70 and energization of the primary winding of thetransformer 60 in the same manner as would the closing of one of theswitches 50, a, 50b, and 500.

Since the igniter 48 is now connected across the terminals of thesecondary winding of the transformer current will flow through theigniter 48 raising its temperature sutficiently to provide for theignition of fuel flowing from the pilot burner 30. The igniter 48 willremain energized until the time delay switch 76 interrupts the holdingcircuit of the control relay to cause opening of the main switch 68 anddeenergization of the primary winding of the transformer 60. The thermalelement 32 of the safety shut-off device 28 will respond to the presenceof flame at the pilot burner 30 to condition the safety shut-off device28 to admit fuel to the oven burner g3 where it will be ignited by theflame at the pilot burner It will be apparent that switching means maybe connected in series with the igniters 44 and 46 and operativelyassociated with the cooks 38, 38a, 38b, and 380, in the same manner asthe switch 62 is associated with the oven burner cock 28 so that theigniters 44, 46 may be selectively energized.

While a relatively simple ignition system for multiple fuel burners hasbeen described and shown it will be apparent that many changes can bemade in the arrangement and combination of parts and in the details ofconstruction herein disclosed within the scope of the appended claimswithout departing from the spirit of the invention.

It is claimed and desired to secure by Letters Patent:

1. An ignition system for a plurality of fuel burners having a source ofelectrical energy and comprising a plurality of electrical resistanceigniters in parallel circuit, at least one switch means movable betweenopen and closed positions and connected in series with at least one ofsaid igniters, a plurality of manually operable fuel controlling meansadapted to be connected respectively with said burners and beingrespectively movable between fuel flow permitting and fuel flowpreventing positions, main switch means movable between open and closedpositions for controlling the energization of said circuit, anelectrical relay for actuating said main switch means, a plurality ofnormally open switches in parallel circuit, said last named circuitbeing connected in series with the coil of said relay and with saidsource, a plurality of means respectively associated with said fuelcontrolling means and said normally open switches for momentarilyclosing each of said normally open switches upon movement of the fuelcontrolling means associated therewith from fuel flow preventingposition to fuel flow permitting position to thereby energize said relayand close said main switch means, a holding circuit for said relayadapted to be completed with the closing of said main switch means, atime delav switch in said holding circuit for interrupting said holdingcircuit upon the expiration of a predetermined period initiated at thecompletion of said holding circuit, and means oneratively associatedwith at least one of said fuel controlling means and with said at leastone switch means for moving said at least one switch means to closedposition upon movement of the fuel controlling means associatedtherewith from fuel fiow preventing position to fuel flow permittingposition.

2. An ignition system for gas ranges having top and oven burners, aplurality of manually operable valves adapted to be connectedrespectively with the burners and being respectively movable betweenfuel flow preventing and fuel flow permitting positions, and a source ofelectrical energy comprising an electrical resistance 35 igniter forsaid top burners, an electrical resistance igniter for said oven burner,switching means movable between open and closed positions and connectedin series circuit with said oven igniter, said top burner igniter beingconnected in parallel circuit with said oven burner igniter and saidswitching means, main switch means for controlling the energization ofsaid parallel circuit, an electrical relay for controlling said mainswitch means, a plurality of normally open switches in parallel circuit,said last named circuit being connected in series with the coil of saidrelay and with said source, a plurality of means respectively associatedwith said fuel controlling means and said normally open switches forcausing momentary closing of each of said normally open switches uponmovement of the valve associated therewith from fuel flow preventingposition to fuel flow permitting position to thereby energize said relayand close said main switch means, means operatively associated with saidswitching means and with that one of said valves connected with saidoven burner for moving said switching means to closed position uponReferences Cited in the file of this patent UNITED STATES PATENTS1,493,070 Evans May 6, 1924 1,635,104 Woods July 5, 1927 1,940,127Herthneck Dec. 19, 1933 2,120,841 McSherry Jan. 6, 1938 2,194,634 BetzMar. 26, 1940 2,212,875 Camp Aug. 27, 1940 2,417,667 Strobel Mar. 18,1947 2,513,257 Strobel June 27. 1950

